attachments to emails can be copied and then pasted into iMessage. So far the only workaround I know of is to email the pdf, open the sent/received email, then copy the pdf attachment, and paste into iMessage.

Actually, there is a way to bypass this. If you hit print, the print screen will pop up. Pinch outward on the preview picture, and it will display another screen. On that screen there is a share button. Click on the share button and you will be able to send it with messages.

Actually, there is a way to bypass this. If you hit print, the print screen will pop up. Pinch outward on the preview picture, and it will display another screen. On that screen there is a share button. Click on the share button and you will be able to send it with messages.